(n.) A gaseous element, colorless, tasteless, and odorless, the lightest known substance, being fourteen and a half times lighter than air (hence its use in filling balloons), and over eleven thousand times lighter than water. It is very abundant, being an ingredient of water and of many other substances, especially those of animal or vegetable origin. It may by produced in many ways, but is chiefly obtained by the action of acids (as sulphuric) on metals, as zinc, iron, etc. It is very inflammable, and is an ingredient of coal gas and water gas. It is standard of chemical equivalents or combining weights, and also of valence, being the typical monad. Symbol H. Atomic weight 1.
Example Sentences:
(1) The hypothesis that proteins are critical targets in free radical mediated cytolysis was tested using U937 mononuclear phagocytes as targets and iron together with hydrogen peroxide to generate radicals.
(2) It has been conformed that catalase from bovine liver eliminates only the pro R hydrogen atom from ethanol.
(3) We investigated the possible contribution made by oropharyngeal microfloral fermentation of ingested carbohydrate to the generation of the early, transient exhaled breath hydrogen rise seen after carbohydrate ingestion.
(4) Hydrogen isotope effects on these mutants indicate that MotA catalyzes proton transfer.
(5) Excessive accumulation of hydrogen ions in the brain may play a pivotal role in initiating the necrosis seen in infarction and following hyperglycemic augmentation of ischemic brain damage.
(6) Studies were conducted in isolated, buffer-perfused rat lungs to determine if prostaglandin (PG) E1 attenuated pulmonary edema provoked by hydrogen peroxide (H2O2).
(7) All N and O atoms except N(3) and O(4') participate in a three-dimensional hydrogen-bonding system.
(8) Both adiphenine.HCl and proadifen.HCl form more stable complexes, suggesting that hydrogen bonding to the carbonyl oxygen by the hydroxyl-group on the rim of the CD ring could be an important contributor to the complexation.
(9) Control mutant S38N has stability essentially the same as that of wild-type lysozyme but hydrogen bonding similar to that of the stabilizing mutant S38D.
(10) High intensity ultrasound also enhances the heterogeneous catalysis of alkene hydrogenation by Ni powders.
(11) An atmosphere of hydrogen eliminates this inhibition in the hydrogenase-containing T. foetus but not in E. invadens which lacks the enzyme.
(12) Vanadate-dependent oxidation of either pyridine nucleotide was inhibited by the addition of either superoxide dismutase or catalase, indicating that both superoxide and hydrogen peroxide may be intermediates in the process.
(13) Our findings suggest that (a) the inclusion of a liquid meal provides a reproducible method of measuring orocaecal transit using the lactulose hydrogen breath test, (b) rapid small bowel transit in thyrotoxicosis may be one factor in the diarrhoea which is a feature of the disease and (c) if altered gut transit is the cause of sluggish bowel habit in hypothyroidism, delay in the colon, and not small bowel, is likely to be responsible.
(14) Stepwise hydrogenation of metal tetradehydrocorrin salts (10 double bonds) yields a series of macrocycles containing 9, 8, 7, 6 and 5 double bonds and conditions necessary to obtain corrins have been established.
(15) For dipeptides containing the amino terminal residues glycine, alanine and phenylalanine, abstraction of the hydrogen from the carbon adjacent to the peptide nitrogen was the major process leading to the spin-adducts.
(16) (7) The first-order radical transformation rates are independent of the (initial) concentration of N3 or peptide and unaffected by urea (as a modifier of hydrogen bond structures).
(17) Intermolecular contacts occur in both oligomers in the minor groove: in the B form through twisted guanine-guanine hydrogen bonding, and in the Z form through base-base stacking and the water network.
(18) Equilibrium-partitioning measurements indicate that the relative affinities of different probes for PC-rich vesicles, in competition with HODMA or DOTAP vesicles, increase with increasing hydrogen-bonding capacity of the probe headgroup in the order PC less than N,N-dimethyl PE less than N-methyl PE less than PE approximately phosphatidyl-2-amino-1-propanol.
(19) When tissue metabolism was irreversibly inhibited by exposure to formaldehyde, hydrogen ion concentration and pCO2 were significantly decreased in the mucosal side of the chamber compared with the viable gall bladder.
(20) Based on the refined atomic coordinates of the tRNAphe in the orthorhombic crystal, on the recent advances in the distance dependence of the ring-current magnetic field effects and on the adopted values for the isolated hydrogen-bonded NH resonances, a computed spectrum consisting of 23 protons was constructed.
Tribasic
Definition:
(a.) Capable of neutralizing three molecules of a monacid base, or their equivalent; having three hydrogen atoms capable of replacement by basic elements on radicals; -- said of certain acids; thus, citric acid is a tribasic acid.
Example Sentences:
(1) Stromelysin consists of three domains the amino terminal propeptide(s) domain contains the tribasic amino acid sequence RRK which is important in the proteolytic activation of this zymogen by trypsin-like serine proteases.
(2) Tribasic calcium phosphate was chosen as a model for solid bone samples, which are stained with doxorubicin in patients who have received long-term doxorubicin therapy.
(3) Four anhydrous composites--(1) tribasic calcium phosphate (TCP 50%) and triethylene glycol dimethacrylate (TEGDM), (2) silanated lithium aluminum silicate (SS, 75%) and TEGDM, (3) barium sulfate [BaSO4 (70%) and poly(methyl methacrylate) (PMMA)], and (4) silane-coated barium glass (SBG) (75%)--and PMMA were employed in the water-sorption studies at 37 degrees C. The effect of 5% 4-META on the diffusion and uptake of water was studied at 37 degrees C. The data conformed approximately to Fick's laws of diffusion.
(4) Subjects ingested either 1 gm of tribasic sodium phosphate or a glucose placebo four times daily for 3 days prior to performing either an incremental maximal cycling test or a simulated 40-km time trial on a computerized race simulator.
(5) Addition of tribasic magnesium phosphate [Mg3(PO4)2 X 8H2O] prevented the repression of cyclase and markedly stimulated cephalosporin production.
(6) The resulting mixture of chelated and unchelated nucleotides and tribasic acids effected coordinated control of citrate synthase, aconitase, isocitrate dehydrogenase, succinyl CoA synthetase, fumarase, and nucleoside diphosphokinase, because Mg2+-chelates are generally substrates whereas unchelated species are inhibitors.
(7) Our data have defined the cleavages for the signal peptide and propeptide and demonstrate that a tribasic sequence can be used to eliminate N-terminal heterogeneity in this molecule.
(8) Cleavage at a tribasic residue processing site generates a urotensin II with the primary structure: Ala-Gly-Thr-Thr-Glu-Cys-Phe-Trp-Lys-Tyr-Cys-Val.
(9) Calcium carbonate, and particularly tribasic calcium phosphate tablets, are not recommended for patients with achlorhydria.
(10) The rare disease of pulmonary alveolar microlithiasis is characterized by innumerable microscopic stones, mainly of tribasic calcium phosphate, within the pulmonary alveoli.
(11) A Langmuir adsorption isotherm at pH 7.4 and the maximum adsorption capacity of tribasic calcium phosphate were established.
(12) The adsorption of doxorubicin hydrochloride, a potent antitumor agent, on solid tribasic calcium phosphate was studied in vitro.
(13) Subjects ingested 1000 mg of tribasic sodium phosphate or a placebo four times daily for 6 d. A maximal running stress test or a 5-mile performance run was performed randomly on either the 3rd or the 6th d. Test sessions were separated by a 2-wk washout period and repeated with alternating phosphate and placebo regimens.
(14) Both forms of tribasic isocitrate, free and metal chelated are used as alternative substrates with different turnover and affinity.
(15) ATP analogues that dissociate only as far as the tribasic form were also able to inhibit channel activity.
(16) In addition, three sites were identified in the mature protein core of STC (two dibasic, one tribasic) that may be acted upon by endopeptidases to produce truncated forms of the hormone.
(17) One peptide equivalent to the previously reported C-terminal CgB (CCB) is released by processing at a tribasic segment.
(18) Hyroxyapatite (HOAp), tribasic calcium phosphate, crystals induced typical signs of inflammation when injected into the footpad of the rat.
(19) An additional derivative, containing the tribasic sequence from the human protein C propeptide preceding Ser+1, was secreted with full processing of the propeptide.
(20) The formation constant of the complex between cadmium and tribasic isocitrate varies from 860 M-1 at mu=0.16 to approximately 24,500 M-1 at infinite dilution.